From f6dda4587cd95e7020cfdb3ecf0c7bad6b9baa9c Mon Sep 17 00:00:00 2001
From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Tue, 14 Oct 2025 12:38:08 +0300
Subject: [PATCH] m4/dovecot.m4, lib: Add ATTR_NONSTRING macro

---
 m4/dovecot.m4    | 11 ++++++++++-
 src/lib/macros.h |  5 +++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/m4/dovecot.m4 b/m4/dovecot.m4
index 3e1aadf004..6e6bdc2101 100644
--- a/m4/dovecot.m4
+++ b/m4/dovecot.m4
@@ -6,7 +6,7 @@ dnl This file is free software; the authors give
 dnl unlimited permission to copy and/or distribute it, with or without
 dnl modifications, as long as this notice is preserved.
 
-# serial 44
+# serial 45
 
 dnl
 dnl Check for support for D_FORTIFY_SOURCE=2
@@ -79,6 +79,15 @@ AC_DEFUN([DC_DOVECOT_CFLAGS],[
         dnl gcc4
         AM_CFLAGS="$AM_CFLAGS -Wstrict-aliasing=2"
       ],[])
+
+    old_cflags=$CFLAGS
+    CFLAGS="$CFLAGS -Werror"
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+      const unsigned char foo[4] __attribute__((nonstring)) = "1234";
+      ]], [[]])],[
+        AC_DEFINE(HAVE_ATTR_NONSTRING,, [define if you have nonstring attribute])
+      ])
+    CFLAGS="$old_cflags"
   ])
 ])
 
diff --git a/src/lib/macros.h b/src/lib/macros.h
index b7c1adc789..ebc1bf23f8 100644
--- a/src/lib/macros.h
+++ b/src/lib/macros.h
@@ -127,6 +127,11 @@
 #else
 #  define ATTR_DEPRECATED(str)
 #endif
+#ifdef HAVE_ATTR_NONSTRING
+#  define ATTR_NONSTRING __attribute__((nonstring))
+#else
+#  define ATTR_NONSTRING
+#endif
 
 /* Macros to provide type safety for callback functions' context parameters.
    This is used like:
-- 
2.47.3